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Modeling shows invasive Salmonella vaccine reduces cases, deaths among children
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A new model used to assess the impact of non-typhoidal Salmonella vaccine campaigns found that implementing a vaccine for invasive strains through analogous strategy to the Haemophilus influenzae type b vaccination program can reduce cases and the resulting deaths among the pediatric population in Bamako, Mali, according to recent findings.
“Lack of information on the reservoirs and vehicles of transmission of [invasive strains of non-typhoidal Salmonella (iNTS)] in sub-Saharan Africa limits opportunities to utilize classic epidemiologic interventions to control iNTS disease,” Kristin Bornstein, MPH, from the center for vaccine development and institute for global health at the University of Maryland School of Medicine, and colleagues wrote. “However, successful vaccination programs implemented to control other invasive diseases prevalent among pediatric populations in Mali and other countries of sub-Saharan Africa have stimulated interest in the development of vaccines to control iNTS disease.”
Because vaccination has proved so effective for other invasive diseases, such as Hib and Streptococcus pneumoniae, among pediatric patients, researchers developed a mathematical model to assess the potential influence of vaccination programs for non-typhoidal Salmonella (NTS), the predominant pathogen among children aged 5 years and younger in Bamako, Mali. The model, called the Markov Chain transmission model, used anonymized data on 515 iNTS patients admitted to a Bamako hospital aged under 5 years, plus general demographic information and information on the efficacy/coverage of other vaccines in Bamako.
The results showed that receiving vaccines covering both Salmonella typhimurium and enteritidis given in either a three-dose schedule or two-dose schedule with later booster as a newborn, would prevent 73% of iNTS cases and avoid 43% of iNTS-caused death. Researchers also found that the impact would be larger and faster if doctors launched a catch-up vaccine campaign targeting older children simultaneously. They noted that the study was limited by the available information, which included only pediatric patients hospitalized with the infections, not children with milder illness who were not hospitalized or children who died from more severe infections at home.
“Our Markov Chain approach was well suited for incorporating the surveillance data representing the currently available numbers of hospitalized iNTS cases, but made the conservative assumption that infection pressure remained constant both in the natural history of the disease and in the face of vaccination,” Bornstein and colleagues wrote. “As more literature is published on the epidemiology of iNTS disease, a more sophisticated computational model can be crafted that incorporates new data, adding further emphasis to the importance of implementing such a vaccine to protect young children against this invasive disease.” – by Savannah Demko
Disclosure: Bornstein reports no relevant financial disclosures. Please see the full study for all other researchers’ relevant financial disclosures.
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